JDOM Document provides methods to easily create elements and attributes. We will set Employee ID as attribute to Employee element and set the namespace for root element Employees. Notice that Employee elements have empty namespace because we set the namespace for root element only. If you want same namespace for all the elements, you need to create them specifically by using the constructor with namespace argument. Also check the use of Format class for pretty printing XML file. We can use it to output XML in compact and raw format also.
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It behaves like Java, it uses Java collections, and it provides a low-cost entry point for using XML. However, it's more than a simple abstraction above those APIs.
JDOM has been made available under an Apache-style, open source license. That license is among the least restrictive software licenses available, enabling developers to use JDOM in creating products without requiring them to release their own products as open source. It is the license model used by the Apache Project, which created the Apache server.
In addition to making the software free, being open source enables the API to take contributions from some of the best Java and XML minds in the industry and to adapt quickly to new standards as they evolve. To be straightforward, the API has to represent the document in a way programmers would expect.
For example, how would a Java programmer expect to get the text content of an element? While technically correct, that design requires the following code to access an element's content:. Wherever possible, JDOM makes the programmer's job easier.
In fact, we expect that JDOM will be fully compliant before the 1. What that rule of thumb does mean is that just because something could be added to the API doesn't mean it will. The API should remain sleek. JDOM's second philosophy is that it should be fast and lightweight. Loading and manipulating documents should be quick, and memory requirements should be low. JDOM's design definitely allows for that. So, do you need JDOM? It's a good question. There are existing standards already, so why invent another one?
The answer is that JDOM solves a problem that the existing standards do not. DOM represents a document tree fully held in memory.
It also must have the same API across multiple languages. Because of those constraints, DOM does not always come naturally to Java developers who expect typical Java capabilities such as method overloading, the use of standard Java object types, and simple set and get methods. DOM also requires lots of processing power and memory, making it untractable for many lightweight Web applications and programs. SAX does not hold a document tree in memory. Instead, it presents a view of the document as a sequence of events.
For example, it reports every time it encounters a begin tag and an end tag. That approach makes it a lightweight API that is good for fast reading. However, the event-view of a document is not intuitive to many of today's server-side, object oriented Java developers.
SAX also does not support modifying the document, nor does it allow random access to the document. It's a lightweight API designed to perform quickly in a small-memory footprint. JDOM also provides a full document view with random access but, surprisingly, it does not require the entire document to be in memory. The API allows for future flyweight implementations that load information only when needed.
Additionally, JDOM supports easy document modification through standard constructors and normal set methods. Document class.
The Document class is a lightweight class that can hold a DocType , multiple ProcessingInstruction objects, a root Element , and Comment objects. You can construct a Document from scratch without needing a factory:.
For now we'll construct our documents from a preexisting file, stream, or URL:. You can build documents from any data source using builder classes found in the org. That approach is very fast basically as fast as SAX , and it is the approach we recommend. Document object. JDOM's speed has the potential to improve significantly upon completion of a deferred builder that scans the XML data source but doesn't fully parse it until the information is requested. For example, element attributes don't need to be parsed until their value is requested.
So, once in memory, documents are not tied to their build tool. The SAXBuilder and DOMBuilder constructors let the user specify if validation should be turned on, as well as which parser class should perform the actual parsing duties. The defaults are to use Apache's open source Xerces parser and to turn off validation.
Each one implements that standard interface by making the right method calls on the backend parser. You can output a Document using an output tool, of which there are several standard ones available. The org. XMLOutputter tool is probably the most commonly used. The SAXOutputter tool is another alternative. The code to output a Document as XML looks like this:. XMLOutputter takes parameters to customize the output. The first parameter is the indentation string; the second parameter indicates whether you should write new lines.
For machine-to-machine communication, you can ignore the niceties of indentation and new lines for the sake of speed:. Now let's look at how to read the details of a Document.
In case you're not an XML guru hey, don't feel bad, you're our target audience , a document type declaration looks like this. Every XML document must have a root element.
That element is the starting point for accessing all the information within the document. You can then access that Element 's attributes for example, the id above , content, and child Element s. XML documents are tree structures, and any Element may contain any number of child Element s. You can obtain an Element 's children with various methods. Using getChild makes it easy to quickly access nested elements when the structure of the XML document is known in advance.
Given that XML:. Just be careful about NullPointerExceptions if the document has not been validated. Children can get their parent using getParent. Attributes are another piece of information that elements hold. They're familiar to any HTML programmer. Part 1. Inheritance versus composition: How to choose. Get started with lambda expressions in Java.
Tutorial series: Android Studio for beginners. What is JPA?
JDOM Write XML File Example from Object
It behaves like Java, it uses Java collections, and it provides a low-cost entry point for using XML. However, it's more than a simple abstraction above those APIs. JDOM has been made available under an Apache-style, open source license. That license is among the least restrictive software licenses available, enabling developers to use JDOM in creating products without requiring them to release their own products as open source. It is the license model used by the Apache Project, which created the Apache server.
How to read XML file in Java – (JDOM Parser)
JDOM provides a way to represent that document for easy and efficient reading, manipulation, and writing. It has a straightforward API, is a lightweight and fast, and is optimized for the Java programmer. To use JDOM, you need to download the library manually. Document; import org. Element; import org. JDOMException; import org. Now a little pic of my little […].
Java JDOM2 – Read XML Example
It is typically a Java developer friendly API. It is Java optimized and it uses Java collections like List and Arrays. It is of low memory footprint and is nearly as fast as SAX. In order to use JDOM parser, you should have jdom.
Java JDOM Parser - Overview
Once binaries are downloaded, include JDOM jar in your project classpath and you are good to start using it. JDOM Document object provides useful methods to get the root element, list of child elements, getting attribute value for an element and getting element value from name. You will get the same output with above methods also because they are just changing the parser and finally returning the same Document. Your email address will not be published. I would love to connect with you personally.